In much of the world, 18 is a milestone, marking the age of majority, the transition to adulthood and the acquisition of full legal capacity. In most of Europe, you can buy alcohol, stand for election, get a tattoo and place a bet.

While in many countries, the legal rights of those crossing the threshold to adulthood haven’t changed that much since the millenium, the social landscape has shifted dramatically, in part due to the internet and smartphones. On top of that, today’s 18-year-olds are facing an uncertain working future, as technological advances disrupt labour markets, eradicating many jobs and creating new and different roles.

In the United Kingdom, some eye-catching official data offers a glimpse into a few of the quirkier ways life has changed for the world's youngest millennials since the millennium. It shows how the group that has been dubbed “generation sensible” are less likely to drink and smoke than people who were a similar age at the start of the millennium, and spend more time on computers and less time watching TV.

Image: ONS

They’re also getting married at a later age and waiting longer to have children. Since 2000 there’s been a drop in the number of babies born to 18-year-old parents, with the birth rate for women falling by 58% between 2000 and 2016, and dropping 41% for men.

While it’s hard to know whether these shifts in the UK translate to global trends, here are three ways that life has changed for most 18-year-olds around the world:

As the millennium began, 18-year-olds around the world could expect to live to nearly 68 years on average. Now that average is 72, according to data from the World Bank.

Even so, where you live has a huge bearing on how long you’ll last, with Japanese life expectancy rising to around 84 years from 81 over the period. Nigerian life expectancy was almost half that, but still climbing, from 46 years to 53 in 2000.

Life expectancy at birth, in years

Image: World Bank

Geography can also make a stark difference within countries. For example, in the UK, where 18-year-olds are expected to live until their late 80s or early 90s, official statistics show that people living in Glasgow, Blackpool and Dundee can expect to live around a decade less than those in Kensington and Chelsea and Buckinghamshire.

2. Enrolling in higher education

Eighteen-year-olds around the world are also more likely to enrol in higher education. As education improves and more people learn to read and write, access to degrees and advanced studies also experiences a boost.

Image: Our World in Data

3. Having fewer children

Globally, the fertility rate has fallen to 2.5 children per woman, from 2.7 in 2000, and the United Nations expects it to fall further in most countries to just below 2 children per woman by the end of the century.

Low fertility rates are now the norm in most parts of the world, with 80% of the world’s population living in countries with a fertility rate below 3 children per woman. The drop goes hand in hand with better healthcare for children and increasing education levels and labour-force participation for women.

Image: UN Population Division, Our World in Data

Preparing for the future

As for the outlook for the world’s youngest adults, the World Economic Forum’s Future of Jobs Report underscores how new technologies are influencing all industries and requiring different skills. In another 18 years, young people are likely to require different skills again: creativity over manual skills, for instance.